Battery contacts are well known and operate to provide a connection between a battery and another circuit or apparatus that requires power from or possibly supplies power to the battery in the case of, for example, a battery charger. Typically due to a relatively short useful life for batteries, such contacts must consider battery replacement, removal, or substitution. The contacts must be arranged to facilitate the replacement, etc. of the battery in a reasonably burden free and reliable manner for the majority of users. Such contacts are known and are available in various configurations.
Battery contacts by there nature are usually or often connected to circuits or other apparatus that inherently generate time varying energy, either voltage or current, wave forms. Often these circuits demand a time varying amount of power from the battery. This power or time varying energy is conducted through the contact and associated structures. These time varying energy wave forms can also be propagated by electromagnetic fields through space from the source circuits to the contacts and associated structures. In either event the battery contacts may facilitate or induce radiate time varying energy when conducting a time varying amount of power or re-radiate such energy when they have been exposed.
Unfortunately this time varying energy while likely desirable at the source of the energy and intended points of reception or where the energy is to be used can have devastating effects, specifically electromagnetic interference, on unintended recipients of the energy. Various approaches, with various attendant problems, are known for providing an electromagnetic shield, for example a conductive enclosure, surrounding the sources or alternatively the unintended recipients of this energy. Among others, one problem with electromagnetic shields arises when any physical openings or ports, such as for battery contacts, are required in the electromagnetic shield.
Historically practitioners have typically taken advantage of relatively large physical spacing, thus inherent path loss, between sources and unintended recipients to avoid, rather than eliminate, potential problems. Concerns about this issue have prompted regulations by the Federal Communications Commission (FCC) establishing the maximum amount of such radiated energy various devices are allowed to exhibit or radiate. Generally minor openings and un-filtered battery contacts, although allowing some radiated energy have been sufficient to comply with FCC regulations. However and assuming compliance, these regulations have proven insufficient for some applications.
Practitioners driven by a demand for small user friendly wireless data communications devices are beginning to combine computing devices and wireless transceivers in small portable packages. In this application extreme measures may be required to assure that energy generated by a wireless transceiver does not interfere with a computing device and equally important that energy generated by the computing device does not interfere with the wireless transceiver. For the reasons noted above one potential source of such energy is the battery contacts or power contacts of either the computer or transceiver.
Filtered battery contacts employing coaxial capacitors disposed about the power conductor are commercially available and may provide satisfactory performance in some applications. However such contacts have not proven to be economically viable in some applications and may be too physically fragile for a portable environment. Clearly a need exists for a cost effective filtered battery contact suitable for portable environments.